This invention relates to methods and means for displaying and evaluating interferograms. In particular, it comprehends an electronic analog inteferogram synthesizer for providing a real time display of any desired optical aberration pattern or any combination of aberration patterns having any given coefficients.
Interferograms are representations of optical interference patterns and are commonly used in evaluating optical systems. The interference pattern of the interferogram results from optical aberrations such as PISTON; X and Y TILT; DEFOCUS; SPHERICAL; COMA; and ASTIGMATISM. In prior art practice these aberrations are generated optically by means in which the optical system wavelength is compared to a reference optical wavelength. The optical system evaluation procedure includes determining which aberration or combination of aberrations are present. It is also necessary to determine the coefficients or magnitudes of each contributing aberration. The reduction and interpretation of interferograms has in the past been a laborious and difficult procedure. Commonly, the optically obtained interferogram information is derived and a computer is programmed to put a surface to the desired data from which aberration information is extracted.
In addition to their use in optical system evaluations interferograms are the subject of study in Universities and other institutions teaching optics and related studies. In such an environment the ability to generate and display in real time any given aberration or combination of aberrations and aberration coefficients would be an invaluable teaching aid and would provide students with experience that would otherwise require years of laboratory work. Currently in order to demonstrate interferograms it is necessary to either show a slide or set up an optical system with a light source from which only a limited number of aberration patterns can be realized.
In view of the foregoing it is apparent that there currently exists the need for improved and simplified methods and means for evaluating optical systems and for extracting aberration information from the interferograms developed in current optical system evaluation practices. There also exists the need in colleges and universities for an interferogram synthesizer that is capable of displaying in real time any selected aberration pattern or combination of aberration patterns.
The present invention is directed toward satisfying these needs.